Written by

Donna Leinwand Leger and Michael Winter
USA TODAY

Female DNA has been found on at least one of the Boston Marathon bombs, but investigators have not determined whose it is or whether it indicates a woman helped the two brothers blamed for the deadly April 15 blasts, USA TODAY has confirmed.

An official, who asked not to be identified because the investigation was ongoing, said there could be multiple explanations, including a store clerk who handled materials that Tamerlan Tsarnaev and his younger brother, Dzhokhar, used to make the bombs, or perhaps genetic material that unwittingly ended up on the explosive devices, perhaps from a ...